Work around issue in dill for wordcount example save_main_session

[charlesccychen]

This change works around a bug in the dill library (uqfoundation/dill#300), where classes fail to unpickle in the main session if its super() is referenced. This change modifies the wordcount example to not use such a reference.

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Post-Commit Tests Status (on master branch)

Lang	SDK	Apex	Dataflow	Flink	Gearpump	Samza	Spark
Go		---	---	---	---	---	---
Java
Python		---			---	---	---

[charlesccychen]

R: @aaltay @tvalentyn @markflyhigh
CC: @robertwb

[charlesccychen]

Run Python PostCommit

[charlesccychen]

Run Python PostCommit

[robertwb]

Nice. Is it worth noting that DoFn doesn't actually have an init method, so this is not a material change?

[charlesccychen]

Run Python PostCommit

[charlesccychen]

@robertwb Thanks, I incorporated your suggestion.

[robertwb]

On second thought, I might just remove this whole thing, so it doesn't distract from the example. (Often the very first example people see.) You're call.

[charlesccychen]

Thanks, I removed it.